Question about timing advance?

[Ronnie_D]

Hello all:

I have finished restoring my 77 650. I am so thrilled to be riding it now!
I am tuning the ignition system and when I have the timing light on the marks and I am checking the timing advance, the timing advance goes way past the advance timing mark.
Is this normal?

Cheers,
Ronnie.

 

[Ronnie_D]

Something odd happened when I posted my question. I have a small icon of my own avatar.
Any one know what that means?

 

[jpdevol]

If you're talking about the green icon, I think it just denotes you're currently online here.

I'm not the foremost mechanical advance expert, others will confirm this: if the marks line-up at F @ idle, they should be near advance @3500rpm. If that's not the case, the springs may be weak and/or the weights worn allowing too much rotation.

 

[sleddog83]

Hello all:

I have finished restoring my 77 650. I am so thrilled to be riding it now!
I am tuning the ignition system and when I have the timing light on the marks and I am checking the timing advance, the timing advance goes way past the advance timing mark.
Is this normal?

Cheers,
Ronnie.

I am guessing on this, since I don't have a points ignition, but I think the timing is set up statically. When you check it with a timing light you are checking it at idle or anywhere up to 1800 rpm. The plate on the crankcase may be different for different model years. best to check some of the manuals. At idle the timing mark should be close to the recommended mark. As you increase rpms, the counterweights will be pushed out by the centrifugal force causing the ignition plate to advance the timing. The timing light will show the mark as advancing. This is normal. At some point the counterweights will hit the end of their movement. I don't know what the advance degree spread is for the points system, probably the same as TCI... basically a 25 degree advance, starting at about 16 deg. If there is anything mechanically wrong with the system, including weak or tight springs, you will have problems. I bet there is info in the tech section on setting up timing.

 

[jpdevol]

I found nothing in the Tech section, but did find a decent discussion of the mechanical advance begining at Post#62 here:
https://www.xs650.com/threads/no-power-over-3000rpm-engine-trouble-xs2-1972-xs650.50599/page-4

Welcome - nice looking bike, congratulations!

 

[Jan_P]

Are we talking a points ignition ?
As a rule of thumb to advanced ignition at high rpm is not a good thing . Can result in engine damage
It can be heard as rough running or knocking even
If you are experienced or an experienced person can listen and adjust . I think most can with some practice.
in short

If to advanced the knocking is louder .. later setting runs more quiet
at idle the rpm gets lower if advanced to much -- and RPM increases advance closer to TDC
If to late the throttle response gets " Soft " it dont answer blipping the throttle. ( Loss of power )

goes way past the advance timing mark. Does not sound good

I would look into that setting it later and checking the throttle response. At the process.
Setting the points gap at spec and then adjust so throttle response is good and advance not to much.
Slightly late is not so dangerous as to advanced.
lean mixture and to advanced can make you a Bus Passenger instead of a Motorcyclist -- is what I have heard.

A video perhaps

 

[grizld1]

OK folks, speculation isn't helpful. First: weak springs may keep the ignition from retarding promptly, but weak springs will not, repeat, not stretch the advance curve. When points dial in correctly at full retard and open to the left of the leftmost timing mark (that's piston holing country, beware!) it's due to worn bob weights in the advance governor (AKA "automatic timing unit"). There are many ways to fix this condition: I like gggGary's best, which involves shimming the tabs that limit travel of the weights. Search and you will find.

 

[Ronnie_D]

I have replaced the springs with MikesXS springs but they seem loose. Also at certain rpm's, the advance unit makes a buzzing noise.
I put back the stock springs but one seems looser than the other.
Probing further...

 

[Ronnie_D]

Well, I seem to have stopped the advance from going past the full advance mark.
I read in this forum that Yamaha had a bulletin out that said to bend the stops in a bit on the advance unit.
I did this in small increments with a round chisel that has a flat end, it worked !
My advance does not go past the limit mark.
I am going to buy a Tri-Spark electronic system for this bike.
I don't trust points any more. lol

Thank you very much for your help with this matter.

ride on....
Ronnie.

 

[Bumblebee]

I'm glad you got this sorted!
I have a Boyer ignition on mine and set the timing based on ease of starting and how it sounded. Figured I had it "close enough"
I was wrong.
Burned a hole in the #2 piston at freeway speed. I then got the privilege of pulling the engine l out and rebuilding the motor.

The moral of the story is:
Use a timing light and make sure it is correct. Too much advance (like I had) is bad.

 

[5twins]

When you bend the advance weight stop tabs that fractures them and they eventually break off. Yamaha may have recommended it at one time long ago, but not any more. You might want to ask about things you plan to do on the forum here before actually doing them, might save some grief and future screw-ups, lol.

 

[grizld1]

There's a reason I recommended gggGary's procedure of shimming the tabs, not bending them. That reason being that sooner or later, and usually sooner, a tab will break off and reposition itself to the bottom of the housing, causing the engine to die. You may want to stay close to home with the bike until you get the Tri-Spark installed--as in within pushing distance.

 

[Ronnie_D]

I bent the tabs to prove a point and it worked.
Thank you for your feedback about bending it.
I don't want to ride it with this ignition system as I have a brand new top end and don't want to hole a piston.
I am ordring a Tri-Spark asap.

 

[Jan_P]

Welding the tabs ??

 

[jpdevol]

Perhaps you could link Gary's method here for future - Iooked for that, looked in Tech and a general search re mechanical advance - all I found was a pertinent but rambling thread I linked above. This thread's title makes a good candidate.

 

[Ronnie_D]

Here is a link to an older topic where they talk about this issue and other timing issues.

https://www.xs650.com/threads/can’t-rotate-r-points-enough-to-set.62330/
Link to topic